Studies on Metal (Cu and Sn) Extraction from the Discarded ... · Vijayaram R, Chandramohan K...

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Volume 4 • Issue 2 • 1000148 J Chem Eng Process Technol ISSN: 2157-7048 JCEPT, an open access journal Research Article Open Access Vijayaram and Chandramohan, J Chem Eng Process Technol 2013, 4:2 DOI: 10.4172/2157-7048.1000148 Research Article Open Access Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as Solvents Vijayaram R* and Dr. Chandramohan K Department Of Chemical Engineering, Kongu Engineering College, Perundurai, Erode, India *Corresponding author: Vijayaram R, Department Of Chemical Engineering, Kongu Engineering College, Perundurai, Erode, India, E-mail: [email protected] Received November 07, 2012; Accepted December 14, 2012; Published December 17, 2012 Citation: Vijayaram R, Chandramohan K (2013) Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as Solvents. J Chem Eng Process Technol 4: 148 doi:10.4172/2157-7048.1000148 Copyright: © 2013 Vijayaram R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract This Project deals with the experimental results of the leaching of metal like Cu and Sn from Printed Circuit Boards (PCB) from obsolete electronic devices by means of leaching using different combinations of acidic mixtures followed by precipitation. Printed circuit boards were dismantled, cut into small pieces, and fed into a Ball mill. The powder obtained was leached by using the aqueous solutions H 2 SO 4 , H 2 SO 4 +HCl, HCl, and HCl+HNO 3 . The lowest values for the percentage of metal extraction were obtained with H 2 SO 4 while the HCl+HNO 3 mixture exhibited an extraction of Sn and Cu in a maximum percentage. Precipitates were obtained at different pH values by neutralizing the leach liquors using NaOH. The HCl+HNO 3 leach system presented the highest recovery values from the powder feed as well as from the leach liquor. Comparing the results for Sn and Cu extraction after 120 minutes obtained with the various leach systems, 3.0 N HCl+1.0 N HNO 3 exhibited the highest percentage values for simultaneous Sn and Cu extraction (93.3%Sn and 92.7% Cu). Keywords: Tin; Copper; Recycling; Electronic scrap; Extraction. Introduction More than millions of electronic devices have been installed over the past two decades. As new and more efficient electronic devices come onto the market, significant numbers of old electronic devices are being scrapped. Likewise, the number of obsolete electronic devices has also been growing. Due to the lack of specialized companies working with the recycling of obsolete electronic devices, such equipment is commonly scrapped in inappropriate disposal areas, together with domestic garbage, with no specialized recycling processes [1]. Printed circuit boards used in electronic devices are composed of different materials, such as polymers, ceramics, and metals, which render the process of scrappers even more difficult. e presence of metals, such as tin and copper, encourages recycling studies from an economic point of view. e Average Percentage availability of metal in PCB is shown in table 1. However, the presence of heavy metals turns this scrap into dangerous residues. is, in turn, demonstrates the need for solutions to this type of residue so as to dispose of it in a proper manner without harming the environment. e recycling of printed circuit boards from obsolete electronic devices is, at present, a fairly new activity, although opportunities are available for expansion in this area. For instance, gold, silver, tin, and copper, among other metals, can be recovered by means of the hydrometallurgical treatment of printed circuit boards [2]. e E-waste can be treated by thermal and non- thermal methods. e Non-thermal method of treatments uses leaching as one of the main stages. Leaching is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy, it is the process of dissolving minerals from an ore or a concentrate, or dissolving constituents from metallurgical products. Lead, tin, and Copper were successfully recovered from alloy wire electronic scrap through acid/alkali leaching and a NaOH solution was added to the leach liquor for metals precipitation. Some researchers have also been working on the recycling of electronic scrap [3]. Recycling e Recycling process can be done by two methods ermal processing In ermal processing the printed circuit boards can be recycled by applying enormous amount of heat. In this process technique three stages are involved. ey are as follows • Pyrolysis • Hydration • Metallurgy Non-thermal processing is is another way of recycling the printed circuit boards. is method is simple and easy to handle the feed materials. is process includes • Dismantling or Disassembly • Grinding or Crushing Metals Percent Availability Copper Aluminium Zinc Tin Nickel Iron Lead Silver 17-19 7-8 0.1 3.25 0.05 2.9 4.0 Traces Table 1: Composition of PCB. Journal of Chemical Engineering & Process Technology J o u r n a l o f C h e m i c a l E n g i n e e r i n g & P r o c e s s T e c h n o l o g y ISSN: 2157-7048

Transcript of Studies on Metal (Cu and Sn) Extraction from the Discarded ... · Vijayaram R, Chandramohan K...

Page 1: Studies on Metal (Cu and Sn) Extraction from the Discarded ... · Vijayaram R, Chandramohan K (2013) Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board

Volume 4 • Issue 2 • 1000148J Chem Eng Process Technol ISSN: 2157-7048 JCEPT, an open access journal

Research Article Open Access

Vijayaram and Chandramohan, J Chem Eng Process Technol 2013, 4:2 DOI: 10.4172/2157-7048.1000148

Research Article Open Access

Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as SolventsVijayaram R* and Dr. Chandramohan KDepartment Of Chemical Engineering, Kongu Engineering College, Perundurai, Erode, India

*Corresponding author: Vijayaram R, Department Of Chemical Engineering, Kongu Engineering College, Perundurai, Erode, India, E-mail: [email protected]

Received November 07, 2012; Accepted December 14, 2012; Published December 17, 2012

Citation: Vijayaram R, Chandramohan K (2013) Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as Solvents. J Chem Eng Process Technol 4: 148 doi:10.4172/2157-7048.1000148

Copyright: © 2013 Vijayaram R, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

AbstractThis Project deals with the experimental results of the leaching of metal like Cu and Sn from Printed Circuit Boards

(PCB) from obsolete electronic devices by means of leaching using different combinations of acidic mixtures followed by precipitation. Printed circuit boards were dismantled, cut into small pieces, and fed into a Ball mill. The powder obtained was leached by using the aqueous solutions H2SO4, H2SO4+HCl, HCl, and HCl+HNO3. The lowest values for the percentage of metal extraction were obtained with H2SO4 while the HCl+HNO3 mixture exhibited an extraction of Sn and Cu in a maximum percentage. Precipitates were obtained at different pH values by neutralizing the leach liquors using NaOH. The HCl+HNO3 leach system presented the highest recovery values from the powder feed as well as from the leach liquor. Comparing the results for Sn and Cu extraction after 120 minutes obtained with the various leach systems, 3.0 N HCl+1.0 N HNO3 exhibited the highest percentage values for simultaneous Sn and Cu extraction (93.3%Sn and 92.7% Cu).

Keywords: Tin; Copper; Recycling; Electronic scrap; Extraction.

IntroductionMore than millions of electronic devices have been installed over

the past two decades. As new and more efficient electronic devices come onto the market, significant numbers of old electronic devices are being scrapped. Likewise, the number of obsolete electronic devices has also been growing. Due to the lack of specialized companies working with the recycling of obsolete electronic devices, such equipment is commonly scrapped in inappropriate disposal areas, together with domestic garbage, with no specialized recycling processes [1].

Printed circuit boards used in electronic devices are composed of different materials, such as polymers, ceramics, and metals, which render the process of scrappers even more difficult. The presence of metals, such as tin and copper, encourages recycling studies from an economic point of view. The Average Percentage availability of metal in PCB is shown in table 1. However, the presence of heavy metals turns this scrap into dangerous residues. This, in turn, demonstrates the need for solutions to this type of residue so as to dispose of it in a proper manner without harming the environment. The recycling of printed circuit boards from obsolete electronic devices is, at present, a fairly new activity, although opportunities are available for expansion in this area. For instance, gold, silver, tin, and copper, among other metals, can be recovered by means of the hydrometallurgical treatment of printed circuit boards [2]. The E-waste can be treated by thermal and non-thermal methods.

The Non-thermal method of treatments uses leaching as one of the main stages. Leaching is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy,

it is the process of dissolving minerals from an ore or a concentrate, or dissolving constituents from metallurgical products.

Lead, tin, and Copper were successfully recovered from alloy wire electronic scrap through acid/alkali leaching and a NaOH solution was added to the leach liquor for metals precipitation. Some researchers have also been working on the recycling of electronic scrap [3].

RecyclingThe Recycling process can be done by two methods

Thermal processing

In Thermal processing the printed circuit boards can be recycled by applying enormous amount of heat. In this process technique three stages are involved. They are as follows

• Pyrolysis

• Hydration

• Metallurgy

Non-thermal processing

This is another way of recycling the printed circuit boards. This method is simple and easy to handle the feed materials. This process includes

• Dismantling or Disassembly

• Grinding or Crushing

Metals Percent AvailabilityCopper

AluminiumZincTin

NickelIronLeadSilver

17-197-80.13.250.052.94.0

Traces

Table 1: Composition of PCB.

Journal of Chemical Engineering & Process TechnologyJournal

of C

hem

ical E

ngineering & Process Technology

ISSN: 2157-7048

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Citation: Vijayaram R, Chandramohan K (2013) Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as Solvents. J Chem Eng Process Technol 4: 148 doi:10.4172/2157-7048.1000148

Volume 4 • Issue 2 • 1000148J Chem Eng Process Technol ISSN: 2157-7048 JCEPT, an open access journal

• Separation

• Chemical Treatment

Materials and MethodsIn this Project we have handled the non-thermal processing

technique as shown in figure 1. The Printed Circuit Board was crushed in a ball mill and sieved to separate according to size of 0.2 mm. The undersized particle was separated which is feed to the Leaching mixture. The powdered PCB was dissolved in a leaching mixture of acids in different combination. Copper and Tin present in the PCB are allowed to dissolve in the acidic solutions. The amount of metals dissolved in the solution can be determined by using the AAS or by the volumetric analysis method. The concentrations of inorganic acids used in these tests are determined by volumetric analysis. The use of high concentrations of acids was allowed to control the experimental costs. About 10 gms of PCB powder was allowed to react with the 100ml of the leach solution of different concentration [4].

The experiments were carried out at 60 ± 2 ºC. Samples of the leach liquor were collected at intervals of 10, 30, 60, and 120 minutes during the experiment. Leach liquor samples were collected, filtered and sent for chemical analysis to determine tin and copper concentration in aqueous solution [5].

Results and DiscussionsTable 2 shows the percentage of copper and Tin Extracted

from different leaching agents. The objective of the experiment is to determine the leaching ability of the inorganic acids at low concentration. Since the concentration of the acid is low, we can use the commercial grade as quite efficiently. Figure 2 and 3 shows the graphical representation of percentage metal (Cu and Sn) extracted versus reaction time. It was found that the leach liquor of concentrations 3.0 N HNO3 and 3.0 N HCl+1.0N HNO3 leach

systems were the most efficient to recover Tin and Copper (93.3% and 92.7%) simultaneously.

Tin and copper content in the powder generated by the processing of PCBs from obsolete electronic devices is 3.25% Sn and 3.5% Cu. Thus the leach can be considered to be highly significant when compared to the content found in primary mineral sources.

The percentage of tin and copper extracted in the 2.18 N H2SO4+3 N HCl (58.2% and 8.5%) leach system showed the lowest results among the leach systems under study, while the 3.0 N HCl+1.0N HNO3 (93.3% and 92.7%) system presented the highest results for simultaneous tin and copper extraction (using one stage leaching).

The precipitates obtained through the neutralization of the leach liquor from the 2.18 N H2SO4+3 N HCl systems exhibited the lowest results for tin and copper recovery from the powder feed and from the leach liquor. The 3.0 N HCl+2.0 N HNO3 systems presented the highest values for simultaneous tin and copper recovery.

Concerning the morphology of the recovered copper, SEM images revealed dendritic growth of the deposits obtained from all three individual acid leaching solutions (Figures 4a, b, c). Specifically, in the case of the copper obtained from the sulphuric acid solution the recovered metal presented Fine dendritic structure with branches of about 80-100 μm (Figure 4a). On the other hand, copper deposited from nitric or hydrochloric acid

Figure 1: The block diagram of the process used in this work.

S.No Leaching mixture % Copper % Tin1 2.18 N H2SO4 + 3 N HCl 8.5 58.22 3 N HCl +1 N HNO3 92.7 93.33 3N HCl 23.8 85.14 2 N HCl + 2 N HNO3 75.85 76.75 3 N HCl + 2N HNO3 46.71 89.486 3 N HNO3 86.95 93.37 2.5 N HCl + 2.5 N HNO3 52.42 92.21

Table 2: Percentage of Cu & Sn obtained from leached acidic solution after 120 min.

Figure 2: Cu recovery vs. reaction Time.

Figure 3: Sn recovery vs reaction Time.

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Citation: Vijayaram R, Chandramohan K (2013) Studies on Metal (Cu and Sn) Extraction from the Discarded Printed Circuit Board by Using Inorganic Acids as Solvents. J Chem Eng Process Technol 4: 148 doi:10.4172/2157-7048.1000148

Volume 4 • Issue 2 • 1000148J Chem Eng Process Technol ISSN: 2157-7048 JCEPT, an open access journal

quantities of complex end-of-life electronic equipment. The global level of production, consumption and recycling induces large flows of both toxic and valuable substances. Although awareness and readiness for implementing and Improvement is increasing rapidly, there are many obstacles to manage end-of-life products safely and effectively in industrializing countries [7]. Support securing economic efficiency and sustainability of e-waste management systems by optimizing the value added and improve the effectiveness of collection and recycling systems.

References

1. Gramatyka P, Nowosielski R, Sakiewicz P (2007) Recycling of waste electrical and electronic equipment JAMME 20: 535-538.

2. Li J, Shrivastava P, Gao Z, Zhang HC (2004) Printed circuit board Recycling: A State of Art survey. Ind Eng Dept 27: 33-42.

3. Havlik T, Orac D, Petranikova M, Miskufova A (2011) Hydrometallurgical treatment of used printed circuit board after thermal treatment. Waste Manag 31: 1542-1546.

4. Agarwal A, Perween M, Shubhajit P, Sahu KK (2011) Recovery of copper from PCB leach solution by solvent extraction. National Metallurgical Laboratory 20-22.

5. Veit HM, Bernardes AM, Ferreira JZ, Tenório JAS, Malfatti CDF (2006) Recovery of copper from printed circuit boards scraps by mechanical processing and electrometallurgy. Journal of Hazardous materials 137: 1704-1709.

6. Masavetas I, Moutsatsou A, Nikolaou E, Spanou S, Zoikis-Karathanasis A, et al. (2009) Production Of Copper Powder From Printed Circuit Boards By Electrodeposition. Global NEST Journal 11: 241-247.

7. Huang K, Guo J, Xu Z (2009) Recycling of waste printed circuit board: A review of current technologies and treatment status in china. Journal of hazardous materials 164: 399-408.

solutions demonstrated a more compact structure although a dendritic structure was conserved [6].

ConclusionE-waste is an emerging issue, driven by the rapidly increasing

(c)

Figure 4: SEM images of recovered copper revealing the dendritic morphology from (a) H2SO4 solution, (b) HNO3 solution, (c) HCl solution.